Without limiting the scope of the invention, its background is described in connection with a multiple channel video sensor having multiple analog video inputs which are sampled in parallel and having a single time multiplexed analog output channel, the output reflecting the value of a single one of the input channels at any particular time, such as might be found in a facsimile machine, as an example.
Heretofore, in this field, the standard method of implementing such a sensor interface was to build a bank of integrator circuits followed by a bank of sample-hold amplifiers, followed by a multiplexer which determines which channel's signal is to be transmitted to the sensor interface output. This approach requires two amplifiers per channel, and it also imposes a requirement that each channel be identically matched to all the others. Further, any normal offset voltages which occur in the sample-hold circuits are transmitted to the output and result in further channel to channel non uniformity.
Accordingly, it is a goal of this invention to create improvements which overcome the requirement of channel matching, the sensitivity to offset voltages in the sample-hold circuits, and which is more efficient to design, test and manufacture.